It is known to fasten built-in units on switchboards. For this purpose, the built-in units usually have a collar. For fitting purposes, they are plugged into a through-opening (for example an aperture) of the switchboard from the switchboard front side until the collar comes to bear approximately against the switchboard front side. The outer contour (of the rear part) of the built-in unit in this case corresponds in terms of shape and size to the through-opening. The built-in unit is positioned on the switchboard by means of clamps which are positioned at the corners and which also fix the built-in unit. Screws are used for the final fastening. In this case, the collar for sealing the switchboard is provided on the inside with a circumferential injection-molded seal.
It is further known to plug plastic clamps on at the corners of the housing of the built-in unit and to fix and fasten the built-in unit by way of the latching function of the plastic clamps.
One disadvantage with the known fastenings of built-in units is the fact that often a second person is required during fitting, in particular in the case of large switchboards.